Change from a per-session stack of buffers to one global stack which is

much more convenient and also simplifies lot of code. This renders
copy-buffer useless and makes buffer-limit now a server option.

By Tiago Cunha.

server.c

@@ -51,6 +51,8 @@ int		 server_shutdown;
 struct event	 server_ev_accept;
 struct event	 server_ev_second;
 
+struct paste_stack global_buffers;
+
 int		 server_create_socket(void);
 void		 server_loop(void);
 int		 server_should_shutdown(void);
@@ -150,6 +152,7 @@ server_start(void)
 	RB_INIT(&sessions);
 	RB_INIT(&dead_sessions);
 	TAILQ_INIT(&session_groups);
+	ARRAY_INIT(&global_buffers);
 	mode_key_init_trees();
 	key_bindings_init();
 	utf8_build();